This is a new application from an established investigator to investigate structure function relationships of the H+,K+ ATPase. This PI proposes to investigate a new class of acid suppressant medication, imidazo-1,2alpha-pyridnes, which are non-covalent inhibitors of the enzyme. The potential binding sites of SCH28080 and other imidazo-pyridines will be investigated by kinetic measurements in cells transfected with the H+,K+ ATPase and mutated enzyme. Specific membrane segments involved in recognition of this class of inhibitors will be identified. Models will largely rely on the recently identified crystal structure of sr Ca ATPase and Neurospora H+ ATPases, thus the current proposal will refine the model that currently is proposed and maybe used to generate structure-function data for understanding the ion transport role of H+,K+ ATPase and its regulation by this new class of acid suppressant drugs.